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Email client reference (ports, auth, options)

  • IMAP over SSL/TLS (IMAPS): port 993 (recommended for incoming)
  • IMAP with STARTTLS: port 143 (explicit TLS upgrade; less common)
  • POP3 over SSL/TLS: port 995 (if you use POP3)
  • SMTP (submission) with STARTTLS: port 587 (recommended for outgoing)
  • SMTP over SSL/TLS (SMTPS, legacy): port 465 (accepted by some clients)

Encryption: SSL/TLS vs STARTTLS​

  • SSL/TLS (implicit): TLS is negotiated on connect (ports 993, 995, 465). Use when the client requires TLS on connect.
  • STARTTLS (explicit): connection starts plaintext and is upgraded to TLS (port 587, 143). Preferred for SMTP submission on port 587.

Authentication methods​

  • Passwords / App passwords: when 2FA is enabled, create an app-specific password and use it in apps that don't support 2FA-based flows.
  • OAuth2 is not supported by Clearbox — use app passwords for legacy clients and standard passwords where applicable.
  • Avoid using plaintext authentication without TLS.

IMAP-specific settings​

  • Root folder prefix: some clients require a prefix (e.g., INBOX) — only set if folders don't appear.
  • Folder subscriptions: subscribe to only the folders you need to reduce sync overhead.
  • IMAP IDLE: enables push-style notifications; check your client supports IMAP IDLE for near-real-time updates.
  • Sync window: many clients let you choose how far back to sync messages (30 days, 1 year, etc.) — adjust for storage/ bandwidth.

SMTP-specific settings​

  • Require authentication: outgoing server must authenticate with the same credentials (username/password). OAuth tokens are not supported.
  • Use STARTTLS on port 587; SMTPS on 465 is supported but less recommended.

Client-specific tips​

  • Apple Mail (iOS/macOS): prefer IMAP 993 SSL and SMTP 587 STARTTLS. Check Drafts/Sent mapping if items do not appear where expected.
  • Gmail app (Android/iOS): manual IMAP setup works; Clearbox does not support OAuth so sign in with your account password or an app password (if 2FA enabled). For multiple accounts, ensure background sync and battery optimizations allow IMAP IDLE.
  • Thunderbird: supports app passwords; enable IMAP IDLE and folder subscriptions. Use config editor for advanced folder and namespace settings.
  • Outlook (Windows/Mac): uses Autodiscover where configured; if configuring manually use IMAP 993 and SMTP 587. Check Sent and Drafts mapping in Account settings.
  • Android native Mail / Samsung Email: manual IMAP setup supported; follow device prompts and ensure SSL/TLS is enabled.

Common configurable options in clients​

  • Synchronization frequency / push vs fetch
  • Download attachments automatically or on demand
  • Folder sync (which folders to keep synced locally)
  • Signature, auto-reply, and out-of-office settings (client-side)
  • Quota and storage settings (client-side caches)

Troubleshooting checklist​

  • Verify server hostnames and ports (clearbox.alfrolia.com for IMAP/SMTP)
  • Ensure TLS is enabled and certificate names match the server hostname
  • If using 2FA, use an app password
  • If the client reports port blocked, try port 465 or check network/ISP blocking
  • For send failures, ensure SMTP authentication is enabled and the username/password are correct
  • If receiving errors referencing rate limits or too many connections, contact support with timestamps and sample message IDs

Security recommendations​

  • Enable two-factor authentication (2FA) to secure accounts
  • Use app passwords for legacy clients
  • Keep clients and OS up-to-date for TLS and security fixes

Related: setting-up-email-clients, gmail-mobile, outlook-setup